Process of replacing the water in alpha water-moist cellulose by an organic liquid and the product thereof



Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE EKIL HUBERT, ALEXANDER BbST-GRANDE, AND ERICK COBRENS, OF ELBERFELD, GERMANY, ASSIGNORS TO I. -G. FARBENINDUSTBIE AKTIENGESELLSGHAFT,

FRANKIORT-ON-THE-MAIN, GERMANY PROCESS OF REPLACING THE WATER IN A WATER-MOIST CELLULOSE BY AN ORGANIC LIQUID AND THE PRODUCT THEREOF 1T0 Drawing. Application filed March 16, 1927, Serial No. 175,921, and in Germany larch 17, 1926.

The present-invention relates to a cellulose having a large surface and which is impregnated with an organic liquid and to a process for preparing the same.

5 It is known that in many processes in which cellulose is used as starting material the cellulose must be subjected to a special pre-treatment in order to give it a larger surface and a higher reactivity. For many purposes it is not necessary to isolate the pretreated cellulose, but it is suflicient to produce a cellulose which is impregnated with an organic liquid which is to be used as a reaction component or as diluent in the aftertreatment of the cellulose. I

\Ve have now found that a cellulose possessing a large surface, a high reactivity and which is impregnated with an organic liquid is obtainable in a simple and inexpensive aomanner by subjecting cellulose to the swelling action of water or an aqueous liquid and then replacing the water, in case an aqueous solution of a swelling agent is used after previously washing out the swelling agent, by the desired organic liquid as for instance acetic acid, benzene, pyridine, etc. Inasmuch as the organic liquids in question do not exert an swellin action, it is surprising that the arge surface of the cellulose as obtained by the swelling action of the water is not dimlnished in ournew process. I

The replacement of the water by the organic liquids can be effected in several ways. We prefer to press the moist cellulose into a cake and while the pressure is continued, to force the organic liquid through the compressed cake. When moist cotton, for instance is hydraulically pressed together into a cylindrical cake and then acetic acid is forced through this compressed cake from one side, it will be observed that at first at the opposite side the greater-part of the ,water contained in the cotton is expelled substantially freefrom acid whatever. On the 4 appearance of the first traces of acid the receiver is changed, then the concentration of the acetic acid in the expressed liquid rises quickly to 90 to 100% before an amount is collected equal to the halfweight of the dry cellulose; the water in the cotton is thereby practically replaced by acetic acid. When cellulose is employed in this process which has been previously treated. in a hollander or with chemical agents exerting a merceriz'ing eflect'such as solutions of alkali metal salts or of acids or by both methods and has thus acquired a very large capacity for swelling and a very large reaction surface an extraor-- dinarilyreactive cellulose is obtained by the apphcation of suitable organic liquids.

The following example will illustrate the principle underlying our invention, which is not, of course, limited thereto 2- Ear-ample 1.70 grams of bucked and bleached cotton obtainable e. g. after the washing out of bleaching lyes, are pressed in a bronze cylinder of about 20 cm. length and 4.2 cm. internal diameter. The cylinder is closed at the lower end by means of a sieve plate bearing a cloth upon which the pulp is filtered oil by suction and pressed down to a cake of 86 ccm. content which contains 44 grams of water. The pressed cake is then covered with glacial acetic acid and a pressure of 0.3 0.05 atmospheres above the ordinary pressure is thereupon exerted upon the apparatus. 25 grams of water are first expressed. On the appearance of the first trace of acid the liquid is collected 5 grams The first six portions of liquidcollected amount to a total of 30 grams of liquid containing about 16 to 17 grams-of acetic acid, and since the seventh portion contains more than 95% acetic acid thereplacement of the water by acetic acid is complete and. after lightly loosening the mass the same is available for further treatment, as for example for acetylation. When desired the cellulose containin acetic acid can be further compressed so as to represent the initial volume of from 86 ccm. in order to obviate the presence of too much acetic acid operating as a diluent in the acetylation.

Instead of pure acetic acid, acetic acid containing sulphuric acid or another substance suitable as catalyst in a subsequent acetylation process can be emplo ed. Likewise other organic li uids, sue or example as formic acid, pyri inc and the like, WhlCh. are miscible with water and are required in the subsequent reaction can be employed in an analogous manner for the replacement of the water. If on the other hand it is intended to saturate the cellulose with a liquid, not miscible with water, as for example benzene, a double replacement becomes necessary. In this case the water is at first replaced by treatment under pressure with, for example, glacial acetic acid; if necessary, the cake is once more pressed together, and then the glacial acetic acid is replaced by treatment under pressure with benzene. Instead of glacial acetic acid, any other organic liquid which is miscible both with water and benzene, may be used, for example, pyridine, alcohol and the like.

In the technical application of the process a suitably constructed hydraulic replacer is used. When working with glacial acetic acid it will be preferable to arrange the replacement from below upwards, in order to utilize the diiference in specific gravity between water and glacial acetic acid. The degree of applied pressure depends essential- 1y on the staple of the cellulose employed and t 1e requisite capillarity. The rate of the effective pressure in the replacement and the speed at which the liquid is expressed depend primarily on the porosity of the compressed cake of cellulose and on the degree of initially applied pressure.

In the appended claims by the term cellulose we mean water-moist cellulose which has been treated in any way to increase its reaction surface and capacity for swelling, for example, by treatment in a hollander or with chemical agents such as alkali-, saltor acid solutions which exert a mercerizing effector by treatment by both methods and from which the swelling agent has been washed out with water.

We claim 1. The process for impregnating watermoist cellulose with an organic liquid, which com rises (pressing water-moist cellulose into a ca e an forcing out the water by acting upon said cake with an organic liquid under pressure.

2. The process for impregnating watermoist cellulose with an organic liquid, which com rises ressing water-moist cellulose into a ca e an forcing out the water by acting upon said cake with an organic watermiscible liquid under pressure.

3. The rocess for impre ating watermoist cellu ose with an orgamc 1i uid, which comprises pressing water-moist ce lulose into a cake, forcing out the water by acting upon said cake with an organic 1i uid under pressure and forcing out the sai organic liquid with a second liquid which is miscible with the first one but which is not miscible with water.

4. The rocess for impregnating watermoist cel ulose with an organic liquid, which comprises passing water-moist cellulose into a cake and forcing out the water by acting upon said cake with glacial acetic acid under pressure.

5. The process for impregnating watermoist cellulose with an organic liquid, which comprises pressing water-moist cellulose into a ca e, forcing out the Water by acting upon said cake with glacial acetic acid under pressure and forcing out the glacial acetic acid by acting upon the cake under pressure with an organic liquid which is miscible with glacial acetic acid and which is not miscible with water.

6. The process for impregnating watermoist cellulose with an orgamc liquid, which com rises pressing water-moist cellulose into 3. ca e, forcing out the water by acting upon said cake with glacial acetic acid under pressure and forcing out the glacial-acetic acid by acting upon the cake under pressure with benzene.

7. As a new product cellulose impregnated with an organic liquid obtainable according to the process as claimed in claim 2.

8. As a new product cellulose impregnated with an organic liquid obtainable according to the process as claimed in claim 3.

9. As a new product cellulose impregnated with an organic liquid obtainable according to the process as claimed in claim 4.

10. As a new product cellulose impregnated with an organic liquid obtainable according to the process as claimed in claim 5.

11. As a new product cellulose impregnated with an organic liquid obtainable according to the process as claimed in claim 6.

In testimony whereof we have hereunto set our hands.

EMIL HUBERT. ALEXANDER RGST-GRANDE. ERICH CORRENS. 

